The invention relates to a piston pump which is intended for use as a return pump for a slip-controlled vehicle brake system.
Many such piston pumps are known. As an example, German Patent Disclosure DE 40 27 794 A1 can be named. The known piston pump has a pump housing, into which a bush is inserted, in which bush a piston that can be driven to reciprocate is axially received. The piston is a part made by metal-cutting drilling and turning. The production of the piston is therefore complicated and expensive.
The piston of the piston pump according to the invention has a sleeve or a plurality of sleeves that form a circumferential piston wall. This sleeve may be produced by reshaping a piece of pipe, for instance. The piston of the piston pump according to the invention can as a result be manufactured quickly and economically.
Another advantage of the piston pump of the invention is the thin-walled embodiment of its piston because of the use of a sleeve that forms the circumferential piston wall. This has the advantage that the piston has a large-volume interior, which if it communicates with a brake fluid that can be fed by the piston pump forms a damper chamber. This interior damps pressure pulsations and pressure surges in the brake fluid, which in operation are brought about by the piston pump because of its discontinuous pumping mode. This provision improves pumping performance and efficiency of the piston pump, provides noise abatement, and leads to a reduced mechanical strain on the piston pump as well as components hydraulically connected to it. In most cases, a separate vibration damper can be dispensed with.
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings.